MANUFACTURE OF CHLOROPRENE COPOLYMER

PURPOSE:To produce a chloroprene copolymer modified with sulfur having extremely high elongation fatigue resistance and flexing resistance, by dissolving a prescribed amount of sulfur to be used in an appropriate amount of a specific monomer previously, and carrying out the emulsion polymerization of the resulting solution with the solution being added in portions during the emulsion polymerization. CONSTITUTION:When 97-75wt.% 2-chlorobutadiene-1,3 (hereinafter referred to as chloroprene) and 3-25wt.% 2,3-dichlorobutadiene-1,3 monomer are subjected to suspension polymerization using 0.2-1.5pts.wt. sulfur for 100pts.wt. of the monomer, at least 40wt.% above sulfur is previously dissolved in 40-100wt.% above 2,3-dichlorobutadiene-1,3, and the addition is carried out in such a manner that the dissolved substance is added in portions during the period from the beginning of the polymerization to the point where at least 10% of the monomer conversion at which the polymerization is to be stopped are attained. A chloroprene copolymer modified with sulfur which has extremely high elongation fatigue resistance and flexing resistance compared with the prior level is produced.